1. Field of the Invention
The present invention relates to a buck-boost switching regulator, in particular to one with high efficiency, and a method thereof.
2. Description of the Related Art
FIG. 1 shows a conventional buck-boost switching regulator 1, which includes four transistor switches SW1-SW4, controlled by a control circuit 14. The circuit 1 compares a feedback voltage FB obtained from the output terminal with a reference voltage Vref in an error amplifier 12. The control circuit (Ctl. Ckt.) 14 controls the switches SW1-SW4 according to the comparison.
The drawbacks in the prior art are thus. The four switches SW1-SW4 are controlled by the same circuit in the same loop, and they all operate in one given period. Hence the switching loss is high and the efficiency is low. In addition, the overall bandwidth of the switching regulator is limited by the boost mode operation.
In view of the foregoing drawbacks, the present invention proposes a buck-boost switching regulator with high efficiency, and a method for controlling the switching regulator.